The objective of this research is to build and test a Powered Incus Replacement prosthesis (PIRP) for use in individuals with conductive hearing losses (up to 60 dB). This - device is surgically implanted in the middle ear replacing the incus. The PIRP consists of three components. They include; 1) a malleus force sensor, 2) a Signal Conditioning and Power Unit (SCPU), and 3) a stapes driver. The malleus force sensor is attached to the head of the malleus bone and measures the structural dynamics of the eardrum responding to sound. Output from the force sensor is amplified by the SCPU and vibrates the stapes driver. A 3 volt, non-rechargeable lithium cell supplies power to all three components. The proposed PIRP will amplify sound pressure at the eardrum up to 60 dB. A 3 year battery life is expected. A simple surgical procedure can replace the lithium cell. Since the power incus replacement prosthesis is an integral part of the middle ear, the natural dynamic range and frequency response of a healthy middle ear may be restored. The PIRP is also robust and will provide cosmetic appeal. A team consisting of a technical manager, transducer engineer, two ear surgeons and a biomedical engineer, will combine their expertise to 1) determine the operating parameters for the proposed PIRP 2) formulate a suitable final design for each component and 3) fabricate and test a prototype unit. In Phase 1 research, fresh temporal bones will be used to help evaluate the malleus force sensor, stapes driver and SCPU. The proposed Powered Incus Replacement Prosthesis represents a significant advancement in middle ear incus replacement devices and hearing aid implants. The PIRP is totally concealed in the middle ear and requires no daily maintenance. It does not interfere with normal activities like showering, swimming or sleeping. The PIRP measures the "natural" vibration characteristics of the eardrum/malleus.